1. Field of the Invention
The present invention relates to a battery charger for charging a battery and a charge controller therefor.
2. Description of the Prior Art
Hitherto, conventional battery chargers have employed a variety of methods for the purpose of preventing overcharge, for example:
(1) A method of controlling a time period in which the charging current is supplied to a predetermined time period by using a timer.
(2) A method arranged in such a manner that the supply of the charging current is stopped when the voltage of the battery has been raised to a predetermined level.
However, the above-described methods are arranged in such a manner that the charging time or the fully-charged voltage (a voltage at which a further charge is stopped) are previously set. In consequence, a problem arises in that the overcharge stopping operation is allowed to be performed uniformly. However, since batteries respectively have different characteristics, a problem arises in that the battery cannot be charged as desired in a case where the full-charge voltage is not adapted to the individual characteristics. Accordingly, the various types of batteries must respectively be subjected to different operations for setting the charging time and the full-charge voltage. In consequence, an extremely complicated work must be performed.
Recently, a rapid charging system utilizing a large current has been put into practical use in order to shorten the time necessary to complete the charging. However, there is a risk that a gas is generated in the battery since the battery electrolyte will be decomposed when the battery is charged with a large current up to its full-charge level. The gas thus generated will undesirably adhere to the surface of the electrode, causing a problem to be arisen in that charging cannot be completed since the gas acts as an insulating layer at the time of the charging operation.